Fire Safety Cabinets

Over the weekend the element in the main oven of my cooker gave up the ghost. We had a logistical challenge trying to cook the full monty Sunday roast dinner using just the small oven and hob but happily all went well.

I ordered the replacement part from espares a great site that I have used before. They often have cheaper OEM versions and the site includes handy videos showing how to fit common parts.

When I checked the part I found the element pumped out 2500watts and it occurred to me that the cooker was effectively a fireproof cabinet in reverse. Of course the maximum temperature inside is only around 240 deg C way below the 700-1000 degrees generated in a fire but given that the heat is retained for hours on end without raising the exterior skin to dangerous levels it is still pretty impressive although not in the same league as our fireproof flammables storage cabinets.

When choosing a cabinet for storage of flammable substances it’s easy to be confused by the range on offer and particularly what Fireproof actually means. There are three basic cabinet types – Fire Resistant, Flameproof and Fireproof. So what’s the difference?

Fire resistant cabinets are generally compliant with British Standard BS 476. This standard is not based on the fire integrity of the whole cabinet but defines the fire resistant qualities of the materials used in its construction. A fire resistant cabinet to BS470 will be made of materials that will retain their integrity for 30 mins in your average fire at a nominal 750 deg C. Which in plain speak means the materials will not melt or warp. COSHH compliant cabinets for the storage and segregation of hazardous goods – with the exception of flammables – fall into this category but the single skin construction does not prevent the build-up of heat inside the cabinet for any length of time. They are neither guaranteed flameproof or fireproof.

Flame Proof cabinets, often termed flammable(s) storage cabinets, intended specifically for the storage of flammable substances have to comply with the DSEAR (Dangerous Substances and Explosive Atmospheres Regulations 2002) that specifies design features intended to segregate flammable substances from accidental exposure to flames from work activity or accidental fire and to prevent environmental pollution. The joints between the sides, top and bottom of flammables safety cabinets and bins should be seam welded or at least free from openings or gaps, and should be close rebated against the frame such that there is overlap between the frame and lids /doors in their closed position. In addition flammables storage cabinets must have a liquid tight sump with a volume at least 110% of the largest stored container. Tray like spill shelves are also incorporated. The supports and fastenings must be of a material with a melting point greater than 750 deg C. Again these are more often single skin cabinets that are Fire Resistant and Flameproof but not Fireproof.

Fireproof cabinets not only segregate highly flammable substances (HFS’s) as required by COSHH and DSEAR they also protect the contents from the intense heat of a fire for a defined period. BS EN14470-1 is the applicable standard. The multi skinned and insulated construction prevents the interior cabinet temperature from rising above 180 deg C for a set period defined by the fire rating of the cabinet – i.e. from 15 to 90 minutes. These cabinets also have automatic heat activated self closing safety doors and air ventilation /extraction and are commonly used in laboratories and hazardous process industries to safeguard workers and reduce valuable asset losses in the event of fire. The sophisticated fireproof qualities of BS EN14470-1 cabinets allow users to exceed the 50 litres maximum volume of HFS’s recommended for storage in any workroom.